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xiv                     ORIGIN    OF   MARINE   CARNIVORA                   449
terrestrial Carnivora, but the question is,, to which group of
Cariiivora have they the most likeness. The semiaquatic Otter,
and the still more thoroughly aquatic (marine) jEnhydrist
suggest an affinity in that direction. The long body and short
legs of the Otter, which is more thoroughly at home pursuing
fish in the streams than in waddling clumsily upon the banks
of the streams, seem to require but little external change
to convert it into a small Seal, while the long and completely
webbed hind digits of Eriliydris are even more like those of a
Pinniped. The Sea-Lions, in which the external ear has been
preserved, and in which the limbs have not become so entirely
useless for progression on the land as they have in the Seals,
seem to be the intermediate step in the evolution of the latter.
This, however, is not the opinion of Dr. Mivart, who, without
definitely committing himself on the point, presents some evidence
for the assumption that the marine Carnivora are diphyletic.
This double origin, however, is not from two groups of the
terrestrial Carnivora. Dr. Mivarfc, in common with many others,
holds that the Piiinipedia as a whole are undoubtedly nearer to
the Arctoidea than to either of the two remaining sections of
the sub-order. One of the most striking structural characters
in which they show this resemblance is the brain; the peculiar
Ursine lozenge, already treated of as so distinctive a character of
the Arctoidea, is repeated in the Pinnipedia.
There are, however, other points of likeness which seem rather
to point to a Creodont origin. Patriofelis is a genus that from
more than one side may be looked upon as a possible ancestor of
these animals. The Creodont peculiarity of the vertebrae has
already been referred to. It may be added that the facial part
of the skull is small in Patriofelis, which appears, moreover, to
have had an alispheiioid canal. A very remarkable resemblance
lies in the s >ructure of the astragalus. This is not deeply
grooved on the tibial facet as it is in Fissiped Carnivora. This
might be held to be an instance of degeneration in the aquatic Seals,
which do not use their limbs as walking organs. But Professor
Wortman * has pointed out that in the Sea-Otter, which is entirely
aquatic, the groove exists and is plain. The likeness offered to
the Seals by the spreading feet of PatriofeLis is noticed under the
description of that genus.2
1 JBull. Amer. Mus, $Tatt Hist, vf. XS94, p. 129.                  m P. 456 below.
VOL, X                                                                                                     2 G